package org.apache.lucene.search;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.ToStringUtils;

import java.io.IOException;

/** Implements the wildcard search query. Supported wildcards are <code>*</code>, which
 * matches any character sequence (including the empty one), and <code>?</code>,
 * which matches any single character. Note this query can be slow, as it
 * needs to iterate over many terms. In order to prevent extremely slow WildcardQueries,
 * a Wildcard term should not start with one of the wildcards <code>*</code> or
 * <code>?</code>.
 * 
 * <p>This query uses the {@link
 * MultiTermQuery#CONSTANT_SCORE_AUTO_REWRITE_DEFAULT}
 * rewrite method.
 *
 * @see WildcardTermEnum */
public class WildcardQuery extends MultiTermQuery {
    private boolean termContainsWildcard;
    private boolean termIsPrefix;
    protected Term term;

    public WildcardQuery(Term term) {
        this.term = term;
        String text = term.text();
        this.termContainsWildcard = (text.indexOf('*') != -1) || (text.indexOf('?') != -1);
        this.termIsPrefix = termContainsWildcard && (text.indexOf('?') == -1) && (text.indexOf('*') == text.length() - 1);
    }

    @Override
    protected FilteredTermEnum getEnum(IndexReader reader) throws IOException {
        if (termIsPrefix) {
            return new PrefixTermEnum(reader, term.createTerm(term.text().substring(0, term.text().indexOf('*'))));
        } else if (termContainsWildcard) {
            return new WildcardTermEnum(reader, getTerm());
        } else {
            return new SingleTermEnum(reader, getTerm());
        }
    }

    /**
     * Returns the pattern term.
     */
    public Term getTerm() {
        return term;
    }

    /** Prints a user-readable version of this query. */
    @Override
    public String toString(String field) {
        StringBuilder buffer = new StringBuilder();
        if (!term.field().equals(field)) {
            buffer.append(term.field());
            buffer.append(":");
        }
        buffer.append(term.text());
        buffer.append(ToStringUtils.boost(getBoost()));
        return buffer.toString();
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = super.hashCode();
        result = prime * result + ((term == null) ? 0 : term.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (!super.equals(obj))
            return false;
        if (getClass() != obj.getClass())
            return false;
        WildcardQuery other = (WildcardQuery) obj;
        if (term == null) {
            if (other.term != null)
                return false;
        } else if (!term.equals(other.term))
            return false;
        return true;
    }

}
